By Todd Fries, marketing manager—identification systems, HellermannTyton
As we move closer to September, the new NEC 2017 will be published and released, giving the industry a glimpse into many new changes and additions in Article 690. As PV systems grow and evolve, the required labeling must change with it to ensure safe and informative installations. Like any evolving process, input from many sources is required to gain a better understanding of what works and what does not, so the process of change can proceed in a way that makes sense for everyday use in real world applications.
Code making panel 4 of the NEC 2017 reviewed hundreds of public inputs. Each suggestion was weighed, reviewed and compared to other similar requests and then voted up or down based on all relevant data and substantiations. Many suggestions were for improved labeling. In the end, the panel addressed a number of inputs; some of the changes are outlined in this article.
Please note that just because the new NEC 2017 is in effect, each State and or local jurisdiction may not automatically adopt the new code. Many are on specific code review cycles and may continue to enforce earlier revision of the code. Check with your local authorities to be certain which code revision is currently in force before labeling.
New Bipolar PV System Requirements
Making changes that are relevant to existing and future systems is important. Part of the effort has involved addressing labeling efficiency and eliminating or reducing labels that no longer serve a valid purpose. For instance, certain labels are no longer considered necessary, such as the bipolar label listed under 690.7(E)(3) from the NEC 2014 code. Disconnection of the neutral cannot result in overvoltage of the array, since the ground-fault detection system is required to separate the array into two distinct arrays during fault conditions; therefore, condition 3 is unnecessary.
So, to make this more relevant, the NEC 2017 Code Article 690.31(I) will now indicate that a new label shall be used to clearly mark bipolar photovoltaic systems with a warning notice indicating that disconnecting the grounded conductor(s) (not the neutral) could result in overvoltage of the equipment.
This change is linked to the revisions related to solidly grounded and reference grounded systems. The warning about the disconnection of the grounded conductor in a bipolar system is only relevant for solidly grounded bipolar systems, which are extremely rare. The revision in 690.31(I) for the NEC 2017 clarifies (for reference grounded bipolar systems) that these bipolar arrays must be separated into two distinct monopolar arrays when the grounded conductor is interrupted, so overvoltage does not occur.
Simplifying Labeling for Power Information
Another example is in NEC 2014 Article 690.35(F). Originally, this marking requirement was seen as necessary for electricians, based on thinking that ungrounded conductors were somehow safe.
That has never been true and so the requirement for this marking will be eliminated, reducing the number of labels required on a PV system and simplifying the labeling process even more.
Speaking of simplifying labeling, the following labels are still required, but the words “DO NOT TOUCH TERMINALS” have been removed. This is found in 690.17(E) of the NEC 2014 code, but will be found in 690.13 and 690.15 in the new NEC 2017 revision.
As of the first draft revision of NEC 2017, 690.53 has changed to simplify the required power information. When editing current code, the panel typically documents the changes as shown in the bullets you see below. This helps by preserving the current code text, while also showing what was eliminated or changed.
690.53 DIRECT CURRENT PHOTOVOLTAIC POWER SOURCE
- (1) Rated maximum power-point current.
- (2) Rated maximum power-point voltage.
- (3) Maximum system
- Informational Note to (3): See 690.7(A) for maximum PV system voltage.
- (4) Maximum circuit current. Where the PV power source has multiple outputs, items (1) and (4) shall be specified for each output.
- Informational Note to (4): See 690.8(A) for calculation of maximum circuit current.
- (5) Maximum rated output current of the charge controller or dc-to-dc converter (if installed).
The following label already exists in Article 690.55 of the NEC 2014, but the language was clarified slightly so that the new NEC 2017 code now reads: “Energy storage systems shall be marked with the maximum operating voltage, including any equalization voltage. If solidly grounded, grounded circuit conductor shall be marked to indicate the polarity.” The previous code revision simply indicated: “Photovoltaic power systems employing energy storage shall also be marked with the maximum operating voltage, including any equalization voltage and the polarity of the grounded circuit conductor.”
In the NEC 2014, this section of code required the polarity of the grounded conductor to be marked in all cases. In the 2017 code, only solidly grounded systems need the polarity to be marked as part of this provision. Many systems do not have grounded conductors, so the provision in NEC 2014 did not make sense. Also, other marking requirements in 690.31(B) require general markings that include polarity, making this polarity marking requirement redundant. NOTE: SOLIDLY GROUNDED MEANS THAT AC CONDUCTORS ARE USED 99% OF THE TIME.
Changes for Stand-Alone Systems
On a similar note, language was clarified in article 690.56(A) regarding stand-alone systems. References to the AHJ and related codes were removed.
- A) Facilities with Stand-Alone Systems. Any structure or building with a PV power system that is not connected to a utility service source and is a stand-alone system shall have a permanent plaque or directory installed on the exterior of the building or structure at a readily visible location acceptable to the authority having The plaque or directory shall indicate the location of system disconnecting means and that the structure contains a stand-alone electrical power system. The marking shall be in accordance with 690.31(E).
This revision removes subjective content that might be confusing for enforcement personnel. The AHJ, in this case, could be both the building department and the fire department. These different AHJs could have different opinions on location. Simply stating that the sign must be in a readily visible location is preferred. Fire departments are most likely your best choice to consult with on the best placement of the sign. The reference to the wiring methods section of 690 was not appropriate for this sign and was deleted in the code revision.
Regarding the fire department and the fire marshal, one of the more important changes involves how a system is identified for rapid shutdown. The details around rapid shutdown are still being discussed but, regardless of the outcome, fire marshals want clear identification regarding rapid shutdown.
A public input was submitted to NFPA1, which is currently updating the IFC (International Fire Code) for 2018. This input is described below and also applies to the NEC 2017 revision so that there is consistency between both documents.
The new language listed in 690.56(C) will require a label that is similar in concept to the two examples below.
The first label would be required for a PV system that shuts down the array and all conductors leaving the array, which will represent the NEC 2017 rapid shutdown requirements.
The second label would be for PV systems that only shut down the conductors leaving the array, which is representative of the current rapid shutdown requirements defined in the NEC 2014 revision.
The label shall include a simple diagram of a building or roof. Diagram sections in red signify sections of the PV system that are not shut down when rapid shutdown switch is operated. Sections of the diagram in yellow signify sections of the PV system that are shut down when the rapid shutdown switch is operated. Buildings with both types of rapid shutdown, or a system or a PV system with one of the rapid shutdown types and a PV system with no rapid shutdown, shall have a detailed plan view showing each different PV system and a dotted line around areas that remain energized after the rapid shutdown switch is operated.
Finally, the rapid shutdown switch shall have a label located on or no more than 1 meter (3.3 ft.) from the switch that will appear as shown below:
As you can see, there are many changes – both subtle and obvious – that are being considered for the NEC 2017 revision.
The second draft meetings are in November. We will continue to gather feedback so that final changes can be made using public input and validated by associated code references as well as real world requirements.
The goal is to continue working toward better code language that helps installers, inspectors and designers meet the challenges of the future and ensure a safe installation environment.
Todd Fries is a Marketing Manager of Identification Systems with HellermannTyton, North America, in Milwaukee, Wisconsin and also serves on Code Making Panel 4 of the NEC 2017 and is involved with the changes and additions being discussed in this article.